Conventional fuel delivery module flanges for automotive applications are primarily made of acetal or polyacetal polyoxymethylene (POM) since it offers a good balance of cost and performance in the demanding environment for fuel systems. Customers have asked for improved performance, specifically in relation to the resistance of the flange to acids, which may be present in the environment. There are many other available materials which could likely work as a monolayer part, but usually they have some property that makes them unattractive for other reasons, for example, low permeation resistance, reduced impact strength, or significantly higher cost. Likewise, there are other solutions, for example, putting a protective cover over the flange on the fuel tank, but these solutions add cost, assembly difficulty, and may not package in the available space in a vehicle.
The provision of a multilayer flange has been hampered by the ability of materials to adhere to acetal. Acetal tends to be very lubricious, not easily being bonded to by other materials. Leak paths around certain components are also potential failings of a conventional flange configuration. In addition, most development related to flanges has focused on improving permeation or making components of the flanges conductive.
Acetal is considered to be ideal for most characteristics, but for this new acid resistance requirement. Thus, there is a need to provide a multilayer flange containing acetal yet be resistant to acid.